Frequently, homes, offices and industrial plant facilities experience many types of emergency situations involving power failures where an interior or exterior area has no light. Such power failures may result from electrical short circuits, brownouts, fire, accidents, natural disasters (i.e., floods, hurricanes, tornados, etc.) or a planned shutdown of electricity within a facility or dwelling. Many facilities, and especially residential homes, do not have emergency generators to provide temporary backup lighting in such situations and thus are limited to nominal emergency lighting in the form of portable light sources, such as flashlights or lanterns.
Accordingly, a need exists to provide a device for automatic, high-level illumination that is capable of immediate activation in response to a disruption of power. In such emergency situations, it is desirable for the illuminating device to be efficiently powered by a single battery pack, such that it is capable of constant high-level illumination lasting for several days or even weeks. Further, the illuminating device should provide a low-level illumination in response to local motion so as to facilitate the non-emergency transit of a darkened room or corridor. Finally, the illuminating device should be responsive to ambient light such that the above high and low-level illuminations do not occur in daylight or otherwise externally lighted rooms.